UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

The Honorable Jeremiah W. Nixon 

Governor of Missouri 

P.O. Box 720 

Jefferson City, Missouri 65102 

Dear Governor Nixon: 

REGION 7 

11201 RENNER BOULEVARD 

LENEXA, KS 66219 

AUG 1 9 2014 

OFFICE OF 

THE REGIONAL ADMINISTRATOR 

Thank you for your recommendation dated December 10, 2013, of air quality designations for the 2012 

revised primary annual fine particle National Ambient Air Quality Standard throughout Missouri. I 

appreciate the infonnation Missouri shared with the U.S. Enviromnental Protection Agency as we move 

forward to improve PM2.s air quality. This letter is to notify you of the EPA's preliminary response to 

Missouri's recommendation and to inform you of our approach for completing the initial area 

designations for the 2012 revised p1imary annual PM2.s standard. 

On December 14, 2012, the EPA promulgated a revised primary annual PM2.s NAAQS (78 FR 3086, 

January 15, 2013). In that action, the EPA revised the primary annual PM2.s standard, strengthening it 

from 15.0 micrograms per cubic meter (Jlg/m3

) to 12.0 Jlglm3

; retained the existing 24-hour PM2.s 

standard at 35 Jlglm3; retained the existing 24-hour PM10 (coarse particle) standard at 150 Jlg/m3

; and 

retained the current suite of secondary PM standards. The EPA revised the primary annual PM2.s 

standard based on an integrated assessment of an extensive body of new scientific evidence, which 

substantially strengthens our body of knowledge regarding PM2.s-related health effects. The revised 

primary annual PM2.s standard will provide increased protection for children, older adults, persons with 

pre-existing heart and lung disease, and other at-risk populations against an array ofPM2.s-related 

adverse health effects, including premature mortality, increased hospital admissions and emergency 

department visits, and development and exacerbation of chronic respiratory disease. 

History shows us that better health and cleaner air go hand-in-hand with economic growth. Working 

closely with the states and tribes, the EPA is implementing the standards using a commonsense approach 

that improves air quality and minimizes the burden on state, local, and tribal governments. As part of 

this routine process, the EPA is working with the states and tribes to identify areas in the country that 

meet the standards and those that need to take steps to reduce PM2.s air pollution. Within one year of 

promulgating a new or revised air quality standard, the Clean Air Act requires the Governor of each 

state to submit to the EPA a list of all areas in the state, with a designation recommendation for each 

area. As a first step in implementing the 2012 annual PM2.s standard, Governors were to submit their 

designation recommendations, including appropriate area boundaries, by December 13, 2013. 

As required by the Clean Air Act, the EPA then promulgates designations for all areas across the 

country. The EPA designates an area as "nonattainment" if it is violating the 2012 annual PM2.s NAAQS 

or if it is contributing to a violation of the NAAQS in a nearby area. Consistent with designations for 
previous PM2.s standards, the EPA intends to use a designation category of "unclassifiable/attainment" 

for areas that are monitoring attainment or do not have monitors, but for which the EPA has reason to 

believe are likely attainment and are not contributing to nearby violations. Additionally, the EPA intends 

to designate as "unclassifiable" those areas where the EPA cmmot detennine based on available 

infom1ation whether the area is meeting the NAAQS or where EPA bas not detennined that the area 

contributes to a nearby violation. At this time, the EPA is proceeding with intended initial area 

designations using quality-assured, ce1iified air quality monitoring data from 2011 to 2013. 

We have considered the annual PM2.s designation recommendation submitted by Missomi on December 

10, 2013, and have reviewed the relevant technical infonnation, including 2011-2013 air quality data. 

These data do not indicate any violation of the 2012 annual PM2.s NAAQS in Missouri. However, a 

recent EPA-conducted teclmical systems audit of Illinois' monitoring program revealed data 

completeness issues for the State of Illinois which affects Missouri areas/counties. Because of these data 

completeness issues, the EPA cannot determine whether the counties with the incomplete monitoring 

data are meeting or not meeting the NAAQS or whether counties nearby to those counties with 

incomplete monitoring data contribute to a nearby violation. Accordingly, the EPA intends to modify 

Missouri's recommended area designation and designate St. Louis area counties including Franklin, 

Jefferson, St. Louis, St. Louis City and St. Charles counties as unclassifiable. The EPA intends to 

designate the remainder of Missouri as unclassifiable/attaimnent. A Technical Support Document, 

which provides additional detail regarding the status of data for Missouri and the rationale to support the 

EPA's unclassifiable designation, is available on the EPA's website at 

http://www.epa.gov/pmdesignations/20 12standards/state.htm. If Missouri has additional infonnation for 

the EPA to consider, please submit it to us by October 29,2014. 

The EPA will make its preliminary designation decisions and supporting documentation available to the 

general public for review and comment. We will be announcing a 30-day public comment period shortly 

in the Federal Register. After considering the additional infonnation we receive, the EPA plans to 

promulgate final annual PM2.s designations in December of2014. 

The EPA is committed to working with the states and tribes to share the responsibility of reducing PM2.s 

air pollution. Current and upcoming federal standards and safeguards- including pollution reduction 

rules for power plants, vehicles, and fuels- will ensure steady progress to reduce PM2s-fonning 

pollution and will protect public health in communities across the country. We look forward to a 

continued dialogue with you and your staff as we work together to implement the 2012 ammal PM2.s 

standard. Should you have any questions, please do not hesitate to contact me, or have your staff contact 

Becky Weber of my staff at 913-551-7487 or weber.rebecca@epa.gov. 

Sincerely, 

~~l Karl Brooks 

cc: Sara Parker Pauley, Director, Missouri Department ofNatural Resources